The Ear in the Wall eBook

Carton and I followed, fascinated by the minuteness
of his investigation and knowledge.

“You see,” he explained, “when a
voice or a passage of music sounds or is sung before
a phonograph, its modulations received upon the diaphragm
are written by the needle point upon the surface of
the cylinder or disc in a series of fine waving or
zig-zag lines of infinitely varying depth and breadth.

“Close familiarity with such records for about
forty years has taught Mr. Edison the precise meaning
of each slightest variation in the lines. I have
taken up and elaborated his idea. By examining
them under the microscope one can analyze each tone
with mathematical accuracy and can almost hear it—­just
as a musician reading the score of a song can almost
hear the notes.”

“Wonderful,” ejaculated Carton. “And
you mean to say that in that way you can actually
identify a voice?”

Kennedy nodded. “By examining the records
in the laboratory, looking them over under a microscope—­yes.
I can count the overtones, say, in a singing voice,
and it is on the overtones that the richness depends.
I can recognize a voice—­ mathematically.
In short,” Craig concluded enthusiastically,
“it is what you might call the Bertillon measurement,
the finger-print, the portrait parle of the human
voice!”

Incredible as it seemed, we were forced to believe,
for there on the table lay the graphic evidence which
he had just so painstakingly interpreted.

“Who was it?” asked Carton breathlessly.

Kennedy picked up another microphotograph. “That
is the record I took of one of the calls I made—­merely
for the purpose of obtaining samples of voices to
compare with this of the impersonator. The two
agree in every essential detail and none of the others
could be confounded by an expert who studied them.
Your ‘wolf’ was your old friend Kahn!”

“Fighting back at me by his usual underhand
methods,” exclaimed Carton in profound disgust.

“Or else trying himself to get control of the
Black Book,” added Kennedy. “If you
will stop to think a moment, his shafts have been
levelled quite as much at discrediting Langhorne as
yourself. He might hope to kill two birds with
one stone—­and incidentally save himself.”

“You mean that he wants to lay a foundation
now for questioning the accuracy of the Black Book
if it ever comes to light?”

“Perhaps,” assented Kennedy carefully.

“Surely we should take some steps to protect
ourselves from his impostures,” hastened Carton.

“I have no objections to your calling him up
and telling him that we know what he is up to and
can trace it to him—­provided you don’t
tell him how we did it—­yet.”

Carton had seized the telephone and was hastily calling
every place in which Kahn was likely to be. He
was not at either of his offices, nor at Farrell’s,
but at each place successively Carton left a message
which told the story and which he could hardly fail
to receive soon.